Fatigue damage control of mechanical systems

This paper presents the concept and architecture of a fatigue damage control system for mechanical structures. In contrast to the conventional cycle-based approach, fatigue damage is represented via nonlinear differential equations with respect to time in the state-variable setting. This damage model is compatible with the dynamic model of the plant, i.e. the process under operation and control, and the instantaneous damage rate depends on the current level of accumulated damage. The objective here is to achieve an optimized trade-off between dynamic performance and structural durability of the plant. This interdisciplinary effort requires augmentation of the system-theoretic techniques for decision making and control with governing equations and inequality constraints representing the fatigue damage properties of structural materials. The major challenge in the reported work is to characterize the fatigue damage generation process in mechanical structures and then utilize this information for synthesizing algorithms of performance optimization, robust control and risk assessment for plant operation.